Recent content by Evertje

Thanks a lot gabbagabbahey! I have solved the problem :)!

Hi all, I am having trouble with a certain integral, which I got from Quantum Physics by Le Bellac: \int dxdp\;\delta\left( E - \frac{p^2}{2m} - \frac{1}{2}m\omega^2x^2 \right) f(E) The answer to this integral should be 2\pi / \omega\; f(E) . My attempts so far: This integral is basically a...

Hi guys, As I've tried to convey using the topic title, I would like to know if (and how large the effect would be) one gets charged by using an ordinary capacitive touchscreen. From what I've understood, the projective capacitive touchscreens have the conductive layers (the wires I mean)...

Hi all, Consider a simple harmonic oscillator in the ground state. Measuring its energy yields the ground state energy with 100% probability. Now by measuring its position (thereby changing the wavefunction) and next measuring the energy again, there is now a nonzero probability of finding...

Thanks to both of you for the replies. I think I've found my problem and solved it; It comes down to the electrical field inside the capacitor, storing the energy. Since the electric field is the gradient of the potential, I can always just add a constant to the potential (in this case just the...

Thanks for the quick reply! Ok, that part is very much clear to me now. I have attached a quick drawing of the circuit which made me think about this, I know it is not the nicest drawing but ok.. The text that is with this image is somewhat as follows: The inverters work as follows: input...

Hi all, I have the feeling I'm missing something big. Consider first a capacitor having +9V on both terminals, in this case nothing happens. Now I set the negative terminal to 0V, and make sure a current is able to flow; the capacitor will now charge up to 9V, right? Ok, now I make sure...

Interleaving frequency spectra (audio) Hi, I have an audio signal, which I have transformed into the frequency domain. Let's say for simplicity that it contains 1024 samples, sampled at 1024 Samples/s. Now, as a first experiment I add 1024 samples (in the frequency domain!), all with zero...

Hi all, I'm having some trouble understanding the consequences of directly changing the frequencies in the spectrum of an audio signal. Let me give you an example: Let's say I have some audio signal, which I convert to a spectrum (in LabView, using a direct cosine transform (to avoid...